1. Field of the Invention
This invention relates to a disc recording apparatus for subdividing continuous recording data and recording the subdivided recording data in plural data regions, a disc reproducing apparatus for reproducing the continuous recording data subdivided and recorded by the disc recording apparatus, and a disc employed in the disc recording apparatus and the disc recording apparatus.
2. Description of the Prior Art
An optical disc may have a recording capacity larger by two to three orders of magnitude than that of a magnetic disc and may be accessed at a higher speed as compared to a tape-shaped recording medium. Besides, the optical disc is superior in durability, and data recording/reproduction may be made in a contact-free manner on or from the recording medium. For this reason, the optical disc has become very popular in recent years. As such, one optical disc, a so-called compact disc (CD), is known most extensively.
With the compact disc, a data format is prescribed, in which 8-bit-per-symbol signals are converted into 14-bit signals (channel bits)by eight to fourteen modulation (EFM) and each frame is made up of 24 bit synch signals, 14-bit (1-symbol) subcode, 14.times.32 bit (32 symbol) data, such as play data and parity data, and 3 bits each between neighboring symbols, making up a total of 588 bits, with 98 frames making up a subcode block. The absolute address of each subcode block is designated by Q-channel subcode signals, and data such as play data are processed with one subcode block as a unit. Besides, a lead-in region is provided on the compact disc on a radially inner side of a data region in which the play information etc. is recorded. In this lead-in region, there are sequentially recorded, as table-of-contents data or TOC data indicating the recording positions in the data region, a time code indicating the start positions of airs, numbers of a first air and the last air of the disc, an number of the last air and the end position of the last air, which are sub-coded and recorded as sub-code signals of the Q-channel.
On the other hand, in a CD-interactive (CD-I) format, the following levels, shown in Table 1, are prescribed as the modes for recording/reproducing bit-compressed digital audio signals.
TABLE 1 ______________________________________ SAMPL- ING NUMBER OF PLAYBACK LE- FRE- QUANTTZA- BAND- TIME STEREO/ VEL QUENCY TION BITS WIDTH MONAURAL ______________________________________ A 37.8kHz 8 17kHz 2/4 B 37.8kHz 4 17kHz 4/8 C 18.9kHz 4 8.5kHz 8/16 ______________________________________
Referring to Table 1, if a disc recorded with a level B mode is to be reproduced, digital signals of the standard CD-DA format which have been bit-compressed by a factor of about four are reproduced. As a consequence, if all of the recording data are stereo audio compressed data, data may be reproduced over a fourfold time period or four-channel data may be reproduced, such that recording/reproduction over about 70 minutes may be made by an optical disc having a radius of 8 cm or less.
Meanwhile, when a portable, above all, a pocket size headphone stereo device or a similar recording/reproducing device is to be provided, using an optical disc, a disc with a disc diameter of 12 cm and a disc with a disc diameter of 8 cm (a so-called CD single) is prescribed in format. Since the recording/reproducing apparatus is increased excessively in size and is poor in portability with the disc 12 cm in diameter, it may be contemplated to use a disc which is 8 cm or less in diameter. However, the following problem is raised when the pocket size recording/reproducing apparatus is to be constituted with the use of an optical disc 8 cm or less in diameter.
First, in a standard CD format in which an optical disc on which stereo digital PCN audio signals are recorded with a sampling frequency of 44.1 kHz and a number of quantization of bits of 16 is supplied by a producer for solely reproduction by the user (CD-DA format), the playback time (recording time) of the disc 8 cm in diameter is as short as 20 to 22 minutes at the maximum, so that a symphony of a classic music cannot be recorded on the disc. The playback time of 74 minutes or longer, which is similar to that with the current 12 cm CD, is desirable. On the other hand, it is not possible for the user to make recording with the CD-DA system. Besides, the non-contact optical pickup device is vulnerable to mechanical shock and subject to detracking or defocusing when subjected to vibrations. Consequently, if the apparatus is to be of a portable type, it is necessary to take some strong measures for inhibiting any adverse effects on the reproducing operation otherwise caused by detracking or defocusing,
Next, with a CD-MO format, or format employing a recordable magneto-optical disc, as an extension format of the abovementioned CD-DA format the recording/reproducing time of the disc 8 m in diameter is of the order of 20 to 22 minutes, as is that with the CD-DA format. Besides, the optical pickup device is subject to detracking and defocusing as a result of mechanical vibrations, so that it is desired to take measures for inhibiting any adverse effects on the recording or reproducing operations.
Meanwhile, with the above-mentioned CD-I format, the disc is rotationally driven at the same linear velocity as that of the standard CD-DA format so that continuous compressed audio data are reproduced at a rate of one unit per n recording units on the disc. This unit is termed a block or sector, with each block (sector) being made up of 98 frames with a period of 1/75 second. The number n is dependent on the playback time or the bit compression rate of the data and is equal to 4 (n=4) with e.g. the level B stereo mode. Consequently, with the level B stereo mode, a data string EQU SDDDSDDD
where S is an audio sector and D is other sectors, is recorded on the sector-by-sector basis on the disc. However, when actually recording data, the data string undergoes predetermined encoding similar to that applied to the usual CD format audio data, such as error coding and interleaving, so that the data of the audio sector S and data of the data sectors D are arrayed i n a scrambled manner in the recording sectors on the disc. The other data sectors D may include e.g., video or computer data. If bit-compressed audio signals are employed in these data sectors, a data string of cyclically arrayed 4-channel audio sectors S1 to S4, that is a data string [S1, S2, S3, S4, S1, S2, S3, S4], is recorded after encoding on the disc.
In recording and reproducing continuous audio signals, the 4-channel audio signals are linked from the first channel to the fourth channel. Continuous reproduction for a fourfold time interval may be made at this time by reproducing data corresponding to the audio sector S1 from the inner most region to the outer most region of the disc, then reverting to the inner most region for reproducing second channel data corresponding to the audio sector S2 to the outer most region, then reproducing third channel data corresponding to the audio sector S3 from the inner most region to the outer most region of the disc and finally by reproducing data of the fourth channel data corresponding to the audio sector S4 from the inner most region to the outer most region of the disc.
However, for the above-mentioned continuous reproduction, long-distance track jumps need to be made repeatedly for reverting from the outer most region to the inner most region. Since the track jumps cannot be effected instantly, the playback sound is interrupted during this time because of the absence of the playback data. Besides, when recording continuous audio signals, it is not possible to record only signals of, for example, the sector S2, but it becomes necessary to interleave data of the directly neighboring sectors S1 and S3 and other neighboring sectors, so that it becomes necessary to rewrite signals of the recorded sectors, Consequently, it is extremely difficult to record the compressed continuous audio data.
Meanwhile, with the conventional CD-MO format, similarly to the above-mentioned standard CD-DA format, beginning and end addresses are recorded as TOC data. With the CD-MO system, continuous data needs to be recorded in a continuous region because the information is lost by accessing a non-continuous region. Since continuous data cannot be subdivided for recording in plural regions with the customary CD-MO format, recording can be made only in a continuous vacant region if it is desired to re-record data on a track from which previous recording has been erased, or to perform an editing operation. It is assumed that, in the case of a magneto-optical disc having a recordable region of up to 60 minutes, as shown in FIG. 1, first play data are recorded in a data zone D.sub.1 of from 0 minute to 15 minute, and second play data are recorded in a data zone D.sub.3 of from 30 minute to 45 minute, while no data are recorded in a data zone D.sub.2 of from 15 minute to 30 minute or a data zone D.sub.4 of from 45 minute to 60 minute. Referring to FIG. 2, a track number data "1", indicating the first play data, a recording start data "0", a recording start position data .cent.00 minute 00 second 00 frame", a track number data "1" indicating the first play data, a recording end data "0" and a recording start position data "15 minute 04 second 00 frame" are recorded in the lead-in region as the information indicating that the first play data have been recorded in the data region of from 0 minute to 15 minute. Similarly, a track number data "2" indicating the second play data, a recording start data "0", a recording start position data "30 minute 00 second 06 frame", a track number data "2" indicating the second play data, a recording end data "0" and a recording start position data "45 minute 00 second 00 frame" are recorded in the lead-in region as the information indicating that the second play data have been recorded in the data region of from 30 minute to 45 minute. If the third play data are recorded on the magneto-optical disc, recording cannot be made over the vacant data zones D.sub.2 and D.sub.4, but can be made only in the range of the recording capacity of one of the data zones D.sub.2 and D.sub.4.
In view of the above-described status of the art, it is an object of the present invention to provide a disc recording apparatus in which continuous recording data can be subdivided for being recorded in plural data regions.
It is another object of the present invention to provide a disc reproducing apparatus in which continuous recording data subdivided for being recorded on the disc may be reproduced.
It is yet another object of the present invention to provide a disc in which continuous recording data are subdivided and recorded thereon and in which the continuous data recorded in this manner may be reproduced.
The present invention provides a disc recording apparatus in which compressed input data are stored in a memory and read out therefrom in a burst manner for being recorded in a data region of a disc, and in which data indicating the recording contents of said recording region are recorded in a lead-in region of said disc, comprising data recording means for subdividing input continuous compressed data for recording the subdivided data in plural non-continuous data zones on said disc, and lead-in data recording means for recording track number data associated with the continuous compressed data, address data indicating the positions of said data zones associated with said track number data and address data indicating the linking destination of said compressed data recorded in a given data region.
The present invention also provides a disc reproducing apparatus in which continuous recording data are subdivided and recorded in plural data zones of the disc and in which track number data indicating continuous recording data recorded in each data zone, address data indicating the position of each data zone and linking address data indicating the linking destination from one recording zone to another are recorded in a lead-in region of the disc, comprising lead-in data reproducing means for reproducing the track number data, address data and the linking address data from the lead-in region, and reproducing means for reproducing the continuous recording data from the recording zones of said disc based on said track number data, address data and the linking address data reproduced by said lead-in data reproducing means,
The present invention also provides a disc comprising plural recording zones in which continuous recording data are subdivided and recorded in the subdivided state, and a lead-in region in which track number data indicating continuous recording data recorded in each recording zone, address data indicating the position of each data zone, and linking address data indicating the linking destination from one to another data zone are recorded,
In the disc recording apparatus of the present invention, continuous recording data are subdivided and recorded in this state in plural recording zones of the disc, while the track number data indicating the continuous recording data recorded in each data zone, address data indicating the position of each data region and address data indicating the linking destination from one to another data zone.
In the disc reproducing apparatus of the present invention, a disc in which continuous recording data is subdivided and recorded in plural data regions and in which track number data indicating the continuous recording data recorded in each recording zone, address data indicating the position of each data zone and linking address data indicating the linking destination from one to another data zone are recorded in a lead-in region is reproduced by reproducing the track number data, address data and the linking address data from the lead-in region by lead-in data reproducing means, and by reading the continuous recording data from the plural data zones of the disc based on the track number data, address data and the linking address data by reproducing means,
In the disc of the present invention, continuous recording data are subdivided and recorded in plural data zones. On the other hand, track number data indicating the continuous recording data recorded in each data zone, address data indicating the position of each data zone and linking address data indicating the linking destination from one to another data zone are recorded in the lead-in region.